The present invention relates generally to keyboards, including typewriter and computer keyboards.
More specifically, the present invention relates to keyboards having illuminated key members.
Conventional keyboards include a plurality of key members which display symbols, such as alphanumeric keys, on their top surfaces. Moreover, typical modern keyboards for both electric typewriters and computers utilize a make-and-break electrical circuit which is activated by depression of a key member for identifying a particular symbol embedded on the top of the key member.
A problem with prior art keyboards is that it is often difficult to discern the symbol appearing on the top of the key member under poor lighting conditions. This causes the keyboard operator to memorize the key locations or to strain their eyes to operate the keys of the keyboard under low light conditions. This has become a much greater problem in present day society as keyboards have become necessary for everyday use and as keyboard use is not limited primarily to operation by workers in business offices as in the past. As a result of this expansion of keyboard use, more and more operators have less training on keyboards, and correspondingly many keyboard operators utilize a xe2x80x9chunt and peckxe2x80x9d style of keyboard operation.
Moreover, the advent of laptop and notebook computers has resulted in the use of keyboards at places where they were not previously operated. Often these places provide limited light making it difficult for keyboard operators to quickly and easily operate the keyboard. For example, it is a common sight on commercial aircraft to see a passenger slowly hunt and peck at their keyboards continuously looking at the key members to verify that they are in fact pressing the correct keys.
Accordingly, it is clear that there is a need for an apparatus that makes keyboard key members more discernable in low light conditions. Backlighting is commonly used in rubber keypads, membrane switches, rigid panels and the like to make them more visible and discernable. These keypad panels typically make use of light emitting crystals (LECs), liquid emitting diodes (LEDs), and/or fiberoptics for this purpose. Most prior backlit keyboards utilize a light source which is typically transmitted via a fiberoptic cable to the key members of a keypad. For example, U.S. Pat. No. 5,034,602 issued to Garcia, Jr. et al. discloses an optically activated keyboard which uses fiberoptic cables to transmit light to translucent key members. The light is transmitted through the translucent key members where it is emitted from the top of the key cap. Similarly, U.S. Pat. No. 3,886,544 issued to Narodny and U.S. Pat. No. 5,097,396 issued to Myers disclose keyboards which use backlighting. Each key member in connection to a fiberoptic cable which transmits light to a respective key member which thereafter transmits light from the top of the key cap. Additional keyboard and keypad techniques include the LED and LEC backlighting commonly utilized for alarm activator and deactivator keypads wherein each key includes a separate LED or LEC structure embedded in or behind the key member.
Unfortunately, keyboard and keypad backlighting devices which utilize LED, LEC or fiberoptics are relatively expensive to construct. In addition, it is extremely difficult, if not impossible, to route fiberoptics to the keyboard keys of today""s computer systems. For example, it would be particularly difficult to route fiberoptic cables and provide a light source to the key members of today""s notebook computers and palm-sized computer systems.
In addition, the light sources for use with prior art backlit keyboards require substantial power and in some cases, a fan for cooling which draws additional power. These constructions are prohibitive for portable computers such as laptop and notebook computers which draw on the power of a rechargeable battery and where power is at a premium.
Accordingly, it would be highly advantageous to provide a keyboard having illuminated key members suitable for use with today""s computer systems including portable computers.
It would also be highly advantageous to provide a keyboard having illuminated keys which does not require routing of fiberoptic cables to each key member.
In addition, it would be highly advantageous to provide a keyboard having illuminated key members which is light weight, simple and inexpensive to manufacture, and requires low power consumption.
Briefly, in accordance with the invention, I provide an improved keyboard having illuminated key members. The improved keyboard includes a plurality of key members and, preferably, a light channeling membrane. Both the light channeling member and key members are constructed of a substantially translucent material capable of channeling light rays. In addition, the keyboard of the present invention includes a light source optically connected to the light channeling membrane. In operation, the light source produces light rays which are received by the light channeling membrane which underlies the plurality of key members. The light rays are channeled through the light channeling membrane to the key members which receive the light rays at their lower extremities and channel the light rays upwardly to their top surface. Light is then emitted from the top of the key member to either provide illumination around an opaque construction of a symbol displayed on the top surface of the key member, or in the alternative, to emit light rays in the shape of the symbol itself.
In a preferred embodiment, the light channeling membrane and plurality of key members are manufactured of an acrylic plastic for optical clarity, though other materials may be used depending on weight and manufacturing limitations as would be understood by those skilled in the art. For this embodiment, the light channeling membrane includes a plurality of bores, with each bore being constructed for receipt of the key shaft of a corresponding key member. Meanwhile, each key member also includes a key cap having a symbol displayed thereon. Each key member shaft is constructed to extend downwardly and telescopically into a corresponding bore of the light channeling membrane. Light is channeled through the translucent material of the light channeling membrane until it is emitted from cylindrical sidewalls into the membrane""s bores. Light emitted from the bores"" interior sidewalls is received onto the exterior of the shafts of the key members and channeled upwardly through the translucent material of the shaft, to the key caps which are also constructed of a translucent material. The key cap includes an upper surface having an alphanumeric symbol displayed thereon which is illuminated by light passing through the shaft of the key member to provide the desired illuminated alphanumeric symbol. The symbol can be constructed as light emitting or as opaque with the remainder of the top surface being conversely opaque or light emitting, depending on whether the desired symbol is in either a negative or a positive representation thereof.
In a preferred embodiment, the light source is constructed of a substantially planar sheet underlying the light channeling membrane of the keyboard. A preferred construction for the illuminating sheet of the light source is described in U.S. Pat. No. 5,045,755 issued to Appelberg and assigned to E-Lite Technologies, Inc. which is incorporated herein by reference. The illuminating sheet is a split electrode or parallel plate lamp consisting of a main body sandwiched between first and second conductive layers. Application of an alternating current to the planar sheet provides a luminescent sheet which can be adhesively attached to the bottom of the keyboard light channeling membrane. Moreover, the illuminating sheet is sufficiently thin as to not require significant modification to existing computer keyboards designs.
An additional preferred construction of the luminescent sheet can be obtained from MKS, Inc. located in Bridgeton, N.J., USA under the trademark designation Quantaflex. The Quantaflex material is an electroluminescent lamp including luminescent phosphors embedded in the dielectric medium of a capacitor constructed in the form of a sheet. Electrodes, including at least one translucent electrode, form the top and bottom layers of the Quantaflex material. Upon application of an alternating current to the electrodes, the phosphors give off photons producing light in the visible spectrum. An advantage of the Quantaflex material is that the phosphors can be selectively encapsulated between the electrode layers of the luminescent sheet so as to selectively produce patterns of light emitted from the luminescent sheet. For example, for application with the present invention, it is preferred that the Quantaflex material be constructed to produce light only below and/or immediately adjacent to the key members so as to reduce power consumption.
In an additional preferred embodiment, the luminescent sheet is constructed of one the rapidly developing technologies directed to Organic Light Emitting Devices (OLED), Transparent Organic Light Emitting Devices (TOLED), or Flexible Organic Light Emitting Devices (FOLED). These technologies are available to those skilled in the art and will not be described in further detail herein.
In still an additional preferred embodiment, the luminescent sheet is constructed of a substantially translucent material, such as an acrylic plastic, connected to an independent light source such a fiberoptic light source, light emitting diodes, light emitting crystals, etc.
Where the keyboard of the present invention utilizes an illuminating sheet for a light source, the illuminating sheet may be formed with a plurality of holes. The luminescent sheet is then affixed below the light channeling membrane with the bores of the luminescent sheet underlining the bores projecting through the light channeling membrane. This construction permits the shafts of the key members to project through the membrane bores and through the holes of the illuminating sheet. Where the keyboard is constructed for use with a computer, disposed below the illuminating sheet is a elastic diaphragm, for biasing the key members upwardly, and a keyboard circuit board. The circuit board includes a plurality of switches which are closeable upon pressure application such that depression of the key members causes the respective key shafts to project downwardly through the membrane bores and illuminating sheet holes to depress the elastic diaphragm to, in turn, engage the circuit board switches. The closure of a particular circuit board switch results in a corresponding signal being sent to the computer indicating that a particular key member has been depressed.
In an additional embodiment of the present invention, the light source, constructed in the form of a planar luminescent sheet, is disposed between the elastic diaphragm and circuit board. The elastic diaphragm is manufactured of a translucent material so that light emitted upwardly from the luminescent sheet shines upon the bottoms of the key member shafts, and preferably upon the bottom of the upper clamshell member of the keyboard which is also preferably manufactured of a translucent material. For this embodiment, the elastic diaphragm and upper clamshell member cooperate to function as a light channeling membrane to transmit light from the light source to the key members. The light is then channeled through the key members to be transmitted from the tops of their key caps.
In still an additional embodiment of the present invention, the keyboard is constructed with the light source, in the form of a planar luminescent sheet, positioned to underlie the elastic diaphragm and circuit board of the keyboard. The elastic diaphragm and circuit board are manufactured of substantially translucent materials for permitting light emitted from the luminescent sheet to project upwardly through the circuit board and elastic diaphragm to strike the bottom, extremities of the key members. It is preferred that the keyboard include a separate light channeling membrane for channeling light rays to the sidewalls of the key member shafts. However, for this embodiment, the elastic diaphragm and circuit board of the key board may function as the light channeling membrane. Light emitted from the planar sheet is channeled through the translucent material of the elastic diaphragm and circuit board to the key members. The light is then transmitted through the key members to the key member""s upper surface where it is emitted from the top of the key cap in the shape of a character displayed on the key cap.
In still an alternative embodiment, the light source is comprised of one or more fiberoptic cables. The fiberoptic cables are constructed to project light laterally from their cylindrical exterior as opposed to predominantly from their distal extremities. This can be accomplished by notching, knurling, scratching or in other manners to create flaws in the otherwise smooth exterior cylindrical surface of the fiberoptic cable. These flaws have been found to interrupt the transmission of light along the length of the fiberoptic cable and to transmit light laterally from the exterior surface of the fiberoptic cable. For application with the present invention, the fiberoptic cables are routed alongside, below or through the light channeling membrane so that light transmitted through the fiberoptic cable is transmitted laterally to be received by the keyboard light channeling membrane. The light is then channeled through the light channeling membrane and key members so as to be emitted from the upper surface of the key members to illuminate a symbol or character.
Preferably, substantial portions of the keyboard and key members are coated on their exterior surfaces with a reflective opaque coating such as paint or the like where light is not intended to be emitted from their exteriors. For example, it is preferred that the keyboard be coated with an opaque material in the interstitial regions between the key members so that light does not project upwardly between the key members which would cause visual glare to the keyboard operator or which would otherwise detract from the relative illuminescence of the symbols displayed on each of the key members.
It is thus an object of the present invention to provide an inexpensive simple to construct keyboard having illuminating keys.
It is also an object of the present invention to provide a keyboard having illuminated key members suitable for use with today""s computer systems including portable computers.
Moreover, it is an object of the present invention to provide a keyboard having illuminated key members which does not require routing of fiberoptic cables to each key member.
These and other and more specific objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.